For detailed information about the amounts and types of (a) sex and nudity, (b) violence and gore, (c) profanity, (d) alcohol, drugs, and smoking, and (e) frightening and intense scenes in this movie, consult the IMDb Parents Guide for this movie. The Parents Guide for Short Circuit can be found here.

The fifth SAINT (Strategic Artificially Intelligent Nuclear Transport) robot in a series of military prototypes built by Nova Robotics Laboratories is struck by a lightning-induced power surge, gains sentience, and escapes. With the help of animal lover and snack shack owner Stephanie Speck (Ally Sheedy), who at first believes him to be an extraterrestrial, the robot (who refers to himself as "Johnny 5") learns to speak and to read at a rapid pace to satisfy his demand for "input". Certain that 5 is truly alive, Stephanie helps him to escape capture by his inventors Newton Crosby (Steve Guttenberg) and Ben Jabituya (Fisher Stevens), Nova's President Dr. Howard Marner (Austin Pendleton) and security chief Captain Skroeder (G.W. Bailey), and the U.S. Army.

Short Circuit was filmed from a screenplay by S.S. Wilson and Brent Maddock. It was followed by Short Circuit 2 (1988). A remake of Short Circuit, also titled Short Circuit, is currently in development with no release date yet set.

While it may have been the intention of the filmmakers to depict Beasley as missing his left front leg, thus accentuating Stephanie's love for stray animals, that leg can be seen prominently on Stephanie's shoulder when Beasley jumps off the roof into her arms.

All five SAINT robots are seen at the beginning of the movie during the presentation ceremony. #1 accompanied Newton and Ben when they went looking for Stephanie and #5. Robots #1, #2, and #3 were later sent by NOVA to disarm and capture #5, but #5 wound up turning them into the Three Stooges. #4 is not seen again in the movie. Most viewers assume that Skroeder simply chose to leave #4 behind at the facility, either because he figured that they didn't need four robots to bring in #5 or because he wanted to have one prototype left if something went wrong with the others.

NOVA and the Army, armed with M16 rifles and 40mm grenade launchers, descend on Newton, Stephanie, and #5. Newton and Stephanie agree to come out of the van but plead with them not to harm #5. Suddenly, the back of the van opens up and #5 begins running away. The military open fires on him, blasting him to bits as Stephanie and Newton watch with horror. Even Marner, who wanted #5 captured in one piece, is angered by the destruction of years of research and fires Skroeder. The remains of #5 are returned to NOVA, and Stephanie and Newton sadly drive away together in the NOVA van. Having quit his job with NOVA, Newton mentions moving to Montana where his dad has left him 40 acres. "Great idea!", says a familiar voice from the back of the van. Turns out that #5 made a duplicate of himself from spare parts in the van and used it as a decoy. In the final scene, Johnny 5 drives the van while Newton and Stephanie discuss moving themselves, Johnny 5, and all of Stephanie's animals to Montana.